The invention relates to a pipe coupling of the type comprising a C-shaped elastomeric sealing sleeve having a sleeve web and at least two sealing lips which extend toward one another and are supported on the sleeve web; a housing comprising a cylindrical jacket which comprises two end sections which define a gap therebetween; a closure coupled to the housing and comprising at least one tensioning screw operative to constrict the jacket; and an insert sheet inserted between the sleeve and the housing to bridge the gap; wherein the cylindrical jacket and the insert sheet define radially extending end walls, and wherein the sealing lips have a first, larger dimension prior to operation of the closure and a second, smaller dimension after operation of the closure has compressed the sealing sleeve in a circumferential direction such that the sealing sleeve can be installed over a pipe prior to operation of the closure and then firmly pressed against the pipe by the jacket and the closure.
Pipe couplings of this type, as disclosed for example in German Patent 2,428,101 and corresponding U.S. Pat. No. 3,877,733, have revolutionized pipe connection technology. On the one hand, due to the fact that the sealing lips of the pipe coupling are initially larger than the nominal diameter of the pipes to be connected, it is possible for the coupling to be pushed onto one of the pipes in the pre-assembled state and to install the coupling together with the pipes. The pipes can then be placed next to one another and the couplings can be pushed over the joints. On the other hand, when the sealing lips of the pipe coupling are compressed in the circumferential direction by the constrictable housing, the radial thickness of the seal increases so that the seal is not only pressed against the pipe wall by the housing, but also tends to mold itself to the pipe surface. This results in a sealing capability which is fully satisfactory even in the case of a rough or irregular pipe surface and which additionally remains intact for a long time.
One important object of the present invention is to modify the known pipe coupling for higher maximum operating pressures in such a way that the wall thickness of the web does not have to be increased from the viewpoint of the dimensional stability of the housing. It is another object to increase the dimensional stability of the housing by an amount which is greater than that corresponding to the increase in the wall thickness, in which case, inversely, the constrictability of the housing is to be guaranteed even with an increased wall thickness. It is another object to increase pressure resistance of the coupling to extremely high pressures by an actual, so-called "lightweight construction". This is understood to be a construction which is even capable of compensating for the deformability of the housing, which increases with the diameter of the coupling (in orders of magnitude of 2 meters and over), without the wall thickness having to be increased for this purpose. In this case, the support surfaces contacting the seal are intended to be essentially cylindrical and the steel insert sheet for this purpose is intended to remain as thin-walled as possible despite higher pressures.